Molecular Diversity and Amino Acid Evolution in Simulated Carbonaceous Chondrite Parent Bodies

Abstract

In interplanetary bodies, organics are found originating from various environments. We replicate the solid-phase conditions in a laboratory to elucidate the step-by-step evolution of organic matter, spanning from dense molecular cloud ices to processes occurring within meteorite parent bodies. The focus of our work is on amino acids, considered as potential chemical tracers of secondary alteration on asteroids. Using gas chromatography and high-resolution mass spectrometry, trace amounts of amino acids are identified in a preaccretional organic analogue formed from a dense molecular ice analogue. This analogue was subsequently exposed to aqueous alteration. This induced an increase in the formation of αand βamino acids over time. Supported by high-resolution mass spectrometry data, the reactions involved sugars and amine compounds, followed by amino acid destruction due to the Maillard reaction, which consumes both sugars and amino acids. Surprisingly, a second phase of amino acid formation, specifically α-amino acids, was observed, indicating the potential occurrence of the Strecker reaction. We demonstrate the intricate chemical network occurring within the presence of molecular diversity, similar to what might occur during parent body alteration. Therefore, investigations on reactivity within meteorite parent bodies have to take into account their molecular diversity, recognizing potential cross-reactions, as demonstrated in this work.